1. Field of the Invention
The present invention relates to magnetic tape transports utilizing a removable tape cartridge, and more particularly to an arrangement within a cartridge tape transport for loading and positioning a tape cartridge relative to a magnetic transducer assembly.
2. History of the Prior Art
It is known to provide a magnetic tape transport in which a length of tape is driven between opposite reels within a removable tape cartridge in rapid, bidirectional fashion. An example of such a magnetic tape transport is provided by U.S. Pat. No. 4,445,650 of Avra et al, issued May 1, 1984 and commonly assigned with the present application. The Avra et al patent describes a magnetic tape transport of the type ideally suited for data recording backup or "steaming" applications in data processing systems. Constant tape tension is achieved in the face of high speed bidirectional operation by an arrangement utilizing pairs of pulleys of slightly different diameter in conjunction with unidirectional clutches.
The magnetic tape transport described in the Avra et al patent utilizes a tape cartridge containing a length of magnetic tape which extends between and is wound around an opposite pair of reels. Loading of the tape cartridge into the transport is accomplished by inserting the cartridge through a slot in the front of the transport and pushing the cartridge into a desired operative position adjacent a magnetic transducer assembly. A door at the front of the cartridge is cammed into an open position during loading of the cartridge so as to expose the tape packs on the opposite reels for engagement by an opposite pair of capstans which are laterally movable within the deck of the tape transport. Thereafter, driving of the capstans results in driving of the tape packs on the opposite reels within the cartridge so as to advance the length of magnetic tape in a desired direction and at a desired speed relative to the magnetic transducer assembly. The magnetic transducer assembly is mounted so as to be vertically movable into one of a plurality of different possible positions so that the magnetic heads contained therein may address different ones of a plurality of tracks on the length of magnetic tape.
Magnetic tape transports of the type described in the Avra et al patent require relatively precise positioning of the tape cartridge on the deck of the transport so that the heads of the magnetic transducer assembly align with the proper tracks on the tape. The tape which is typically one-half inch in width may have as many as twenty-four different tracks disposed across the width thereof, requiring rather precise positioning of the tape relative to the magnetic transducer assembly in order to align the magnetic heads thereof with one or more of such tracks. Driving of the magnetic tape at nominal speeds on the order of 200 inches per second also requires rather precise positioning of the tape cartridge, as does the need to repeatedly achieve a particular tape wrap angle.
The tape transport described in the Avra et al patent positions the tape cartridge in a desired location within the deck using separate camming and locking arrangements. Following insertion of the tape cartridge through a slot in the front of the transport and into the region of an operative position, a camming arrangement is employed to force the cartridge into the operative position. Lateral movement of the cartridge is restrained by opposite bosses which serve to guide the cartridge into place as it is inserted into the transport. The camming arrangement achieves a desired height or Z axis positioning of the cartridge by pushing upwardly on the base of the cartridge so as to hold the upper surface of the cartridge base against a pair of generally horizontally disposed rods at the front end of the cartridge and against a reference point or surface on the transport housing which receives the top of the cartridge at a rear portion of the cartridge. The cartridge is prevented from sliding out of the operative position by a locking arrangement which includes a spring loaded shaft for engagement within a recess in the base of the cartridge.
While the camming and locking arrangements described in the Avra et al patent serve to position and lock the cartridge in place within the transport in reasonably accurate fashion, they have certain shortcomings, particularly with respect to the ease of loading and unloading of the cartridge. For one thing it is different to achieve the same tape wrap angle with repeated cartridge loadings. Also, tape reel misalignment may occur due to bending of the cartridge base as a result of the nature of the camming and locking arrangements. The camming and locking arrangements require manual actuation thereof.
A more desirable arrangement would be an automatic one which takes over and completes the loading of the cartridge in automatic fashion following partial insertion of the cartridge into the slot in the front of the transport housing and which is capable of releasing the cartridge electronically as well as in response to manually initiated command. Also, the positioning of the cartridge on the deck within the tape transport and relative to the magnetic transducer assembly could be improved by an arrangement which does not rely on opposite bosses or other guide members for correct lateral cartridge positioning but which instead positions the cartridge relative to X and Y axes by different and independent means.
Accordingly, it is an object of the invention to provide improved tape cartridge loading apparatus.
It is a further object of the invention to provide tape cartridge loading apparatus capable of completing the insertion of the tape cartridge into the transport and properly positioning the cartridge therein in automatic fashion and without the need for manual assistance.
It is a still further object of the invention to provide tape cartridge loading apparatus which positions a tape cartridge in a desired location relative to mutually perpendicular X, Y and Z axes automatically and in relatively precise fashion.
It is a still further object of the invention to provide tape cartridge loading apparatus which provides for release of a tape cartridge from a loaded position in automatic fashion and which can be electronically initiated.